地学前缘 ›› 2022, Vol. 29 ›› Issue (5): 88-101.DOI: 10.13745/j.esf.sf.2021.9.17

• 海洋沉积动力学 • 上一篇    下一篇

东海北部陆架表层沉积物重矿物组合、迁移路径对底层水团的示踪响应研究

刘勇1,2(), 李广雪1,2,*()   

  1. 1.中国海洋大学 海洋地球科学学院, 山东 青岛 266100
    2.海底科学与探测技术教育部重点实验室, 山东 青岛 266100
  • 收稿日期:2020-07-12 修回日期:2021-03-28 出版日期:2022-09-25 发布日期:2022-08-24
  • 通讯作者: 李广雪
  • 作者简介:刘 勇(1975—),男,博士,主要从事海洋地质学与海洋沉积学研究工作。E-mail: denverly@ouc.edu.cn
  • 基金资助:
    中国地质调查局我国海域关键地质问题跟踪分析与研究专题项目(DD20160147);中国地质调查局我国海域关键地质问题跟踪分析与研究专题项目(GZH201100202);国家自然科学基金重点项目(41030856);国家自然科学基金重点项目(91858203);泰山学者建设工程专项(GXLI)

Heavy mineral assemblages and migration paths in the surface sediments of the northern East China Sea shelf: Tracer responses to bottom water masses

LIU Yong1,2(), LI Guangxue1,2,*()   

  1. 1. College of Marine Geosciences, Ocean University of China, Qingdao 266100, China
    2. Key Lab of Submarine Geosciences and Prospecting Techniques, Ministry of Education, Qingdao 266100, China
  • Received:2020-07-12 Revised:2021-03-28 Online:2022-09-25 Published:2022-08-24
  • Contact: LI Guangxue

摘要:

基于东海北部陆架表层沉积物的泥温、粒度分析与重矿物鉴定数据,结合末次盛冰期(LGM)以来的东海海平面演化阶段分析,提取高海面期以来底层水团承载的沉积重矿物空间分布规律与信息记录。结果表明优势矿物种的迁移路径与区域环流系统密切相关,进而可示踪东海北部物质的大致输运方向。依据透明矿物(普通角闪石、帘石类、稳定矿物)、金属矿物(不透明矿物)、片状矿物及自生矿物等优势重矿物种迁移路径的判断和讨论,将研究区初步划分为5类矿物区,分别为冷涡矿物区(Ⅰ区)、黄海沿岸流与跨陆架流矿物区(Ⅱ区)、长江冲淡水矿物区(Ⅲ区)、暖流矿物区(Ⅳ区)和复合矿物区(Ⅴ区)。Ⅰ区受济州岛西南冷涡影响显著,高含量的自生黄铁矿指示了强还原的沉积环境;Ⅱ区是黄海沿岸流与跨陆架流(ECSC)南向输运老黄河三角洲物质的重要通道,帘石类矿物、金属矿物、片状矿物的含量变化可指示输运的路径;Ⅲ区是长江冲淡水东扩的重要通道,普通角闪石、片状矿物、石榴石为示踪的特征矿物;Ⅳ区是陆架水团混合了台湾暖流和对马暖流水体的区域,区内“洁净”的暖流水阻隔陆源物质向东输运,其西侧为物源供给侧,形成优势矿物低值区,东侧物质供给匮乏,海侵改造沉积出露,重矿物及优势矿物种呈高值;Ⅴ区是区域环流系统季节性变化与强度差异影响下的复合作用区,区内矿物学特征与邻区相比无明显优势。从矿物迁移路径的角度认识东海北部陆架的物质输运与聚集过程,可进一步理解优势矿物示踪意义与区域环流系统动力环境的响应机制。

关键词: 东海北部陆架, 重矿物, 优势矿物种, 迁移路径, 矿物区

Abstract:

Based on the laboratory measurements of mud temperature, particle size and heavy mineral composition in surface sediments of the northern East China Sea, this paper examines the spatial distribution characteristics and information records of sedimentary heavy minerals carried by the bottom water masses since the sea level rise. The results show that migration paths for dominant mineral species are closely related to the regional circulation system and can be used to trace the material transport directions. Based on the characterization of migration paths for dominant heavy mineral species, such as transparent minerals (ordinary amphibole, epidote, stable minerals), metal minerals (opaque minerals), flake minerals and authigenic minerals, the study area is preliminarily divided into five types of mineral provinces: cold vortex (I), Yellow Sea coastal current and cross-shelf transport current in the East China Sea (ECSC) (II), Yangtze diluted water (III), warm current (IV) and composite (V) mineral provinces. Province I is significantly affected by the cold eddy southwest of Cheju Island, and its high authigenic pyrite content indicates a strong reducing sedimentary environment. Province Ⅱ is the main channel for the southward material transport from the old Yellow River Delta by the Yellow Sea coastal current and ECSC, and epidote minerals, metal minerals and platy minerals are the characteristic minerals indicating the path. Province III is an important channel for the eastward diffusion of the Yangtze diluted water, and common amphibole, platy mineral and garnet are the characteristic tracer minerals. Province IV is impacted by the “water barrier” from the mixing of the Taiwan and Tsushima Warm Currents with the continental shelf water masses, where its western part receives the provenance supply and forms the dominant low-value minerals and relatively high-value biogenic detrital, while its eastern part, without provenance supply, produces dominant high-value minerals from the exposed transgressive deposition. And province V is jointly affected by the seasonal variation and differential intensity of regional circulation, showing no significant mineralogical differences compared to neighboring regions in terms of heavy mineral assemblages and dominant mineral contents. Studying the material transport and accumulation processes in the northern East China Sea from the perspective of mineral migration path can help to further understand the significance of dominant mineral tracing and its response mechanism to the dynamic environment of the regional circulation system.

Key words: northern East China Sea shelf, heavy-mineral, dominant mineral species, migration path, mineral province

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